Tag this under The Ghost of Done." These are projects that, for one reason or another, will never get done because my skillset has drifted so far away from the skills necessary to produce them that I'm unlikely to have the time, bandwidth, or skillset necessary to go back and revisit them.
"Terabytes Of XML, Indexed & Compressed." I almost got hired for this idea alone, once upon a time, but sadly I was working already and had no desire to move to Boston. TOXIC is a simple idea: Very large stores of text, like those used for publishing corporations, libraries, governments and the like, live in gigantic SGML and XML databases. There exists a known set of tools for indexing large corpora of texts, and the most common is to use Huffman compression on both an index of terms and their location in the library. The idea is that pulling the index off-disk and decompressing it, caching the result as needed, is faster than pulling an already uncompressed index off disk. Likewise, because Huffman encoding can be resumed at arbitrary points in a compressed library, it's faster to seek to a known compression point, uncompressing the block there, and seeking for the indexed term. What I wanted was to sandwich a second index between the first and the corpus, with an equally compressed representation of the XPaths to desired sections of the corpora. It's such an obvious schtick that I'm surprised no one has done it for an open-source solution.
One of my stories involves a sentient doll, only 30cms tall, who starts out as the companion to a little girl on a planet where the infrastructure experiences a massive and complete systemic breakdown. The doll, the last artificial intelligence on the planet, has to fight her way through bugs, mice, rats and nastier things in her goal of saving her person and restarting her planet's infrastructure. I wanted to write a first-person shooter on the same theme, but lacked the skills or time at the time. I wanted her to have the squeaky voice of an anime character, to be dressed in pink and frills, and to show how that costume became more and more ragged and dirty, as she grew into her role. There's a similar PS/2 game, although it's third-person and poorly done, Hoi-Hoi San, and it was never released in the US. I wanted something good.
Seam-Carving, also known as "content-aware resizing," is the algorithmic reduction of an image by creating maps, either horizontal or vertical, describing paths from top-to-bottom or left-to-right, in which, for each path, the neighboring pixel differential is added up into an overlain entropy map, and then the path with the lowest entropy is removed. This is done systematically until the image has been cropped down to the desired size, with the pixels that represent the least amount of information loss being removed and the seam smoothed over. While it's not perfect, as you can see in the wikipedia example, it might be useful in a number of settings. I still use the Portable Anymap programs on a regular basis, and adding seam-carving to the manipulations would be a useful addition.